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The LaSalle Causeway lift bridge is a 100 year old highway bridge that is integral to the transportation network of Kingston, Ontario, Canada. Rehabilitation of the bridge was planned to address corrosion of the bottom chord and a gap identified at the support of the lifting end. To determine the effectiveness of this rehabilitation, the displacements of the bridge were monitored before and after the rehabilitation, during a static load test, and under regular traffic loading. Since the bridge crosses the Cataraqui River, there are no stationary reference points near midspan from which to measure displacement using conventional sensors. For this reason, digital image correlation was selected as an appropriate monitoring technology. Displacements at the midspan and supports of the bridge were recorded and used to assess the performance of the bridge. The results of this research indicate that the bridge complies with displacement limits and that the rehabilitation of the bridge was successful in rehabilitating the support conditions of the bridge.

The objective of this study was to evaluate the change in the barrier performance of a geosynthetic clay liner (GCL) as a result of desiccation due to dehumidification at 55°C. Specimens of GCL that were damaged by desiccation were scanned using a micro-focused X-ray computed tomography (CT) scanner, and crack generation under two different dehumidification conditions was examined using the results of image analysis. Permeability tests were performed to estimate the hydraulic conductivity of GCL damaged by desiccation with respect to a calcium chloride solution. The results obtained indicate that dehumidification and a space between a GCL and a membrane sheet are key factors in the generation of cracks in the bentonite layer of a GCL at 55°C.

No abstract